Hydrophilic rubber composition

ABSTRACT

A waterproofing membrane system comprising a mixture of dry rubber granules with dry expansive material granules, the mixture adhered to a membrane in a layer. The rubber particles act to limit expansion of the expansive granules in each layer when the membrane is introduced to a source of moisture. Making an expansive sheet waterproofing system comprises determining a desired waterproofing and expansion need by mixing of the rubber granules with dry expansive granules and applying the mixture as a layer to a substrate having an adhesive coating thereon. The coating resulting in the rubber particles limiting expansion of the expansive granules when exposing the prepared membrane to a source of moisture. The membrane retains flexibility and waterproofing, durability and strength of the membrane is increased.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. provisional patent application Ser. No. 61/681,807, filed Aug. 10, 2012, the content of which is hereby incorporated by reference in its entirety.

BACKGROUND

Expandable waterproofing products have evolved into a large segment of the commercial waterproofing industry worldwide. Multiple manufacturers, distributors and applicators have been in search of the right combination of products, formulations, sheeting, and protective scrim capable of resolving variable and complicated product integrity issues arising from product damage encountered after installing expandable waterproofing products. In the days, weeks and months after initial installation, traditional expandable waterproofing products often warp or degrade.

Presently, expandable waterproofing products incorporate a method of quilting two sheets together, forming a sandwich surrounding a chosen expansive material. The quilting is a method used to prevent free expansion of the expansive material, while doubling as foot and machinery traffic surface. A needle punching method comprises a needle that punches a U-shaped tip through a lofted, polypropylene, nonwoven, expansive median (typically Bentonite Clay) and continues through another nonwoven, woven or other base sheet. The U-shaped needed elongates or straightens the once entangled polypropylene strands, attaching the top sheet, through the expansive medium material and penetrating the base sheet. Interlocking will then vary depending on the frequency of needle punches, strand tensile strength and anchoring of the strand on the other side of the base sheet material. These types of needle punched products are most common in both the commercial waterproofing and liner containment markets.

However, these products are engineered with a flaw. The continuous perforation of the base sheet required in order to achieve expansive material containment also provides avenues for water to enter the material and travel, creating elevated levels of water vapor transmission into the structure and surrounding the structure. An undamaged or unperforated base sheet membrane has 10,000 times less water vapor transmission than the use of expansive clays alone, or sandwiched between two porous sheets.

The expandables generally absorb the water and the individual granules expand, such that when the granules are traditionally assembled in layers, on sheets of waterproofing membranes, the introduction of water or other moisture causes the granules to expand and push away from one another. The result, after water or moisture introduction, is a saturated waterproofing membrane in which the expandables have pushed against each other and after saturated, typical expansion results in detachment of membranes from the granules adhered. Thus, the waterproofing membrane is no longer usable.

The existing expandable waterproofing products are prone to damage by pre-hydration from foot or machine traffic, including traffic related to preparation and installation of the waterproofing membranes. This means once installed, the waterproofing membrane is already at a limited capacity as the waterproofing products are exposed to moisture and thus water has been absorbed before the product is even installed for intended use. Once expandable waterproofing products are prematurely hydrated, blemished or rendered ineffective in sealing water with respect to original, pre-installation performance capabilities and expectations, the waterproofing materials or membranes need to be repaired or replaced all together. Further, prior to completed installation, prolonged moisture exposure or submersion of sheet waterproofing systems typically occurs over weekends or during breaks in construction work. After prolonged soaking, workers walk directly over the expanded sheets, further displacing factory manufactured thickness and further compromising the products' overall ability to consistently seal across entire surface areas with equal expandable sealant capacity. Every step on a pre-expanded waterproofing sheet extrudes the expandable material away from its pressure, resulting in displacement and reduction in overall performance and waterproofing integrity.

Many combinations of variables also contribute to the degradation of expandable sheet waterproofing products after installation. The primary post installation culprit is inclimate weather saturation. After hydration has occurred, the entire waterproofing system is compromised and often, the result is partial, if not full, removal and replacement required of the previously installed expandable waterproofing sheeting. Additional problems can arise once an expandable waterproofing sheet has been installed since the membrane is no longer easily accessible for repair and/or replacement. It is difficult and time consuming to replace waterproofing sheets that have been encased under or behind rebar, rendering it inaccessible for removal or replacement.

Standard emulsions adhesives used to adhere or set present waterproofing membranes have a typical solids content ranging from 40 to 60% by weight. The high ratio of 40-60% of water is needed to suspend its solids content during transportation and or application of emulsion adhesive to various surfaces. When emulsion adhesives are used to adhere expansive raw materials such as Bentonite Clay or Super Absorbent Polymers, the water content of the adhesive emulsion is delivered at the same time as its adhesive solids. This ratio of water and adhesive solids cannot effectively contain the expansive materials overwhelming expansive nature. The more adhesive that is applied to the expansive material, an equal or greater amount of water is also distributed at the same time.

This Dual delivery of water at the same time as the adhesive only further activates the expansive qualities of the granules. The greater the quantity of water absorbed by the expansive material, the greater its overall physical size becomes. As the expansive material is continuously fed water, the expansive granule layer is weakened and becomes less dense, while it expands to a gel or another expanded version of itself. In all cases the expansive material becomes more viscous and more prone to future displacement. The pre-expansion of expansive materials such as Bentonite clay and super absorbent polymers represents the first downward step in product sealing performance and the one which can never be reversed.

Subsequently, many expandable waterproofing sheet systems are simply left in place and covered with concrete, despite the obvious compromise in future sheet sealant performance. This conflict is usually the result of financial considerations as well as penalties associated with construction delays. The biggest challenge facing all expandable sheet waterproofing products lie in the ability of the sheet waterproofing material to maintain a consistent performance standard after job site installation when compared to original expected performance ranges, pre-installation.

BRIEF SUMMARY OF THE INVENTION

The present disclosure relates to a waterproofing membrane system comprising a mixture of dry rubber granules, dry expansive material granules, an adhesive and a membrane. The dry rubber granules are mixed with the dry expansive material granules, and then applied to the membrane in at least a first layer such that the rubber particles limit expansion of the expandables in the layer when the membrane is introduced to a source of moisture. An adhesive is used to adhere the mixture to the membrane. The waterproofing membrane may further limit expansion by comprising a mixture of granules containing 25-90% rubber particles by weight while the expandables may comprise Bentonite clay granules, super absorbent polymer particles or a combination of both granules.

The present disclosure also relates to a method of making an expansive sheet waterproofing system comprising determining a desired waterproofing and expansion need and pulverizing recycled rubber into granules, drying the rubber granules, and then mixing the rubber granules with dry granules of expansive material. The method further comprises applying the mixture of rubber granules and expansive materials as a layer to a substrate having an adhesive coating thereon and the rubber particles limiting expansion of the expansive granules in the layer when exposing the membrane to a source of moisture. Additional layers may be applied by applying an adhesive layer between layers of the granule mixture. In one example, to further limit expansion, the mixture of granules may contain 25-90% rubber particles by weight while the expandables may comprise Bentonite clay granules, super absorbent polymer particles or a combination of both granules.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded side view of a waterproofing membrane comprising the waterproofing composition of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention comprises an expandable waterproofing system, the system comprising a composition of recycled pulverized rubber granules mixed with granules of an expandable. The resulting composition is then adhered to a membrane or other substrate for use as a waterproofing sheet or membrane. The membrane of the present system effectively delays, and possibly prevents hydrophilic expansion of expandable material granules which increases sheet flexibility, increases foot traffic wear resistance, and as such results in overall improvements in appearance, durability, strength and waterproofing performance while inhibiting tearing and/or prehydration of the waterproofing membrane.

More specifically, the present system comprises a specific blend of recycled rubber (typically 40-mesh recycled automobile tire rubber) mixed with an expandable granular. Granular Bentonite clay (typically 30 to 16 mesh granular Bentonite) may be used. The expansive granules may also include, but are not limited to Super Absorbent Polymers including polyacrylate and/or polyacrylimide granules. The system may use any combination or blend of expandables, depending on the needs of the waterproofing system.

The system of the present invention further includes a method by which the rubber granules are coated with an emulsion adhesive or pressure sensitive adhesive. The adhesive coats a circumference of a rubber granule, and thus surrounds a preferred particle size ranging from 16 to 40 mesh sized granular recycled rubber. The adhesive coated rubber particles then assume larger mass space of coverage, while maintaining the pliability, elongation, similar tack strength and similar qualities to emulsion adhesives, while covering a much larger surface area, using a lower amount of adhesive fluid. As the overall surface and mass area of the emulsion adhesive is enlarged, the mass to water content ratio also changes. The water ratio is minimized and a diminishing water content ratio is achieved. The recycled rubber used is flexible, durable and adheres well to other particles after an emulsion adhesive is applied.

The system of the present invention also reduces the amount of water needed in preparing waterproofing membrane construction while increasing the flexibility and durability of the waterproofing membrane, such that the membrane is able to remain intact and retain waterproofing capability far beyond present systems. The system further comprises an increase in overall rubber solids, by concentration, and simultaneously reducing water typically included with the use of emulsion adhesions. The system also maintains the use of standard emulsion base additives or adhesives. The overall usage and performance ranges are expanded, while reducing costs during usage. The concentration of rubber content is expanded far beyond that of an acrylic emulsion or asphaltic emulsion capability during various sheet product manufacturing processes.

More specifically, the rubber granules when prepared with an adhesive coating may be pre-dried prior to adhesive application, and should be dry when coated with the adhesive. Thus, the granules become sticky, and able to adhere to additional granules. Dry granules of expandables are then mixed with the adhesive coated rubber granules, forming a mixture wherein the granules stick together. Heat may be added when mixing to further ensure no additional water remains, and to further eliminate pre-hydration and expansion of the expandables.

The rubber is introduced to the mixture to essentially inhibit any destruction of the waterproofing expandables from the pressure created as the expandables take on moisture and expand against each other. The rubber granules have coated and surround the expandables such that when the expandables try to expand, the expansion is prevented by the strength of the rubber emulsion combination. Wherein a raw expandable will reach full moisture capacity within hours, an expandable surrounded by the adhesive coated rubber granules may take days to reach full moisture capacity, and if the ratio of rubber and adhesive to expandables if great enough for the intended use of the waterproofing membrane, the expandables may never reach full moisture capacity.

Generally, compositions of 50-95% rubber granules by weight exhibit the highest expansion limiting characteristics. More specifically, rubber compositions of greater than 75% by weight may inhibit expansion such that the expandables within a waterproofing composition will not tear, rip or otherwise be blown apart as a result of expansion.

The waterproofing composition includes substituting parts of the emulsion adhesive, and thus reducing the percentage of initial water content of the waterproofing composition, with rubber particles. The rubber particles used may be recycled automobile tire or other rubber. However, any suitable rubber material may be used. The composition may also comprise acrylic adhesives or any suitable adhesive that is substantially tacky, or sticky. The addition of rubber particles, or granules, not only adds flexibility to the waterproofing system, but also mimics the properties of PSA or other emulsion adhesives, while reducing, if not eliminating the need for the addition of water. The rubber, when used in the waterproofing system minimizes the amount of water available to expandable materials when producing the system which also allows the system to withstand far greater submersion or contact with water or other absorbable liquids than traditional waterproofing membranes. The rubber as added to the waterproofing composition prevents or extends hydration time.

As illustrated in FIG. 1, the system of the present invention further comprises adhering the waterproofing composition to a membrane, substrate, flexible backing or other suitable support means 120. The composition is adhered in layers 140, wherein a first layer of adhesive or glue is applied to a membrane 120 and a first layer of the granule waterproofing composition is applied thereon. On top of the first waterproofing composition layer a second layer of adhesive of glue may be applied and then a second layer of waterproofing composition is applied thereon. Additional layers or other combinations of the composition and adhesive may be used per the intended application needs of the waterproofing membrane. The thickness of each waterproofing composition layer will depend on the adhesive coated rubber 160 to expansive granule 180 ratio used in the composition and the desired waterproofing abilities, as well as the intended use of the manufactured waterproofing membrane 100. Each waterproofing composition layer is approximately 30-125 mil in thickness. The granules are kept as dry as possible throughout the system assembly process, and heat or other moisture eliminating processes may also be added such that the environment is water free by evaporation prior to adhering to the membrane.

When assembling sheets of expansive materials as described above, the waterproofing composition includes the recycled rubber particulates of an adequate size to bridge the thickness of the expansive materials (Bentonite clay or other super absorbent polymer) from the substrate base sheet to the top of the assembled product with a single granular size.

The waterproofing composition serves to form a layer wherein the rubber granules and the expansive material are staggered or mixed within each single layer.

In an additional embodiment, a waterproofing membrane may be formed by layering recycled rubber granules alternately with expansive materials during the manufacturing process.

In a further embodiment, to meet enhanced desired expansion capacities of waterproofing membranes, the expansion capacity, and thus waterproofing composition, of each layer can be altered independently. As such, each layer may comprise a varied composition by rubber or expansives content or weight ratio.

The waterproofing system described herein can be used across various applications. The expansive sheet waterproofing materials can be utilized in various new products, ranging from flat or textured impermeable traffic bearing membranes, the membranes being laminated with the expansive coating composition to fabrics, to high performance slower swelling water stops, and engineered to exact expansion capability tapes. The composition as adhered to base sheets or other substrates results in enhanced performance with respect to foot traffic, machinery durability and weather resistance. Alternate selections of base sheets or substrates can further enhance performance. The waterproofing system may further incorporate the use of smooth polyethylene membranes as a base sheet for various expansive material products. Additionally, a textured base sheet may be incorporated or substituted in place of a smooth base material. The texturing of the base sheet or substrate increases the total surface area available for the expansive material to attach or adhere to, and further results in the creation of an interlocking cast pattern capable of greater prevention of expansive material displacement and increased weather resistance.

The composition can also be adhered to a flexible, adhesive backed substrate such that the result is a “peel-n-stick” expansive waterproofing sheet capable of both expansive sealing of membrane breaches with engineered appropriate percentages of rubber while able to self adhere by removal of a barrier sheet over the adhesive coated backside of the sheet waterproofing.

Additional base or substrates compatible with the waterproofing composition and variations described throughout this specification include base sheets that are woven, nonwoven, comprise netting or a release liner or any combination thereof. Both permeable base sheets and impermeable membranes are compatible for adhesion of the waterproofing composition. One an appropriate base sheet or membrane has been determined, the specifications of the waterproofing composition layers including the rubber to expansives ratio of each layer and the amount of layers, as well as adhesive are determined.

The waterproofing membrane with the hydrophilic rubber composition adhered thereto can also be used as non-slip, expandable traction sheets, compression resistant expandable waterproofing sheets used on side slopes of landfills as liners or maybe installed over, under or in between concrete that is cast in place or prefabricated. The fully adhered expansive sheet product is also easily capable of submersion in water or water based liquids, without back pressure or detachment of the composition from the surface or substrate it is attached or adhered to.

In most uses of waterproofing membranes, a termination bar is used to hold the sheet or membrane tight against a wall or other terminating point. At the wall, the membrane is not coated with any expandable materials, and only an adhesive layer remains, which is used to adhere to the wall. When the waterproofing membrane system of the present invention is used, the rubber/expandables composition may be applied to the entire sheet or membrane since the possibility of full expansion is eliminated and thus there is no threat of the membrane or sheet ripping away from a wall and allowing moisture to enter. The present system eliminates expansion in all directions on a membrane.

The present invention further includes a method for increasing and engineering to specific ratios the composition comprising the emulsion adhesive, recycled tire rubber and expansive materials. The composition allows for far greater expansion, water resistance/containment and flexibility beyond that of the capability of existing emulsion adhesives and their containment ability. The greater the ratio of rubber content in the composition, the lower the amount of expansion will result after submersion. Conversely, a greater ratio of expansive material results in greater overall swelling. Overall sheet durability, compression resistance, peel strength all follow the same logic.

EXAMPLE 1

Typical emulsion adhesive usage for expansive sheet products is approximately 1 to 2 pounds of fluid adhesive per 5 square feet of sheet coverage and contains approximately 5 pounds of expansive raw material during the manufacturing process of various waterproofing membranes. Since the emulsion adhesive consists of approximately 50% water by weight, the solids or rubber content of the emulsion adhesive ratio results in approximately 0.5 to 1 pound of adhesive rubber solids per 5 square feet and/or 5 pounds of overall expansive material processed.

Using the waterproofing composition of the present disclosure, the same proportion of 1 to 2 pounds of “fluid” emulsion adhesive can be elevated to a rubber content containing approximately 0.75 to 4.75 pounds of rubber solids (recycled rubber particles) per 5 square feet and/or 5 pounds of overall expansive material. Both examples contain the same ratio of 0.5 to 1 pound of water per 5 square feet of coverage and/or use of 5 pounds of expansive material.

The system containing 0.75 to 4.75 pounds of rubber solids per 5 square feet and/or 5 pounds of expansive material is required to engineer specific blends of expansive material capable of fully adhering to various substrates. This includes creating self-ballasted sheets for above or below grade uses, installation of expansive sheets unconfined or confined, improved durability to sustain machinery and foot traffic with minimal displacement, and engineered delayed hydration of expansive material while increasing strength, sheer, elongation and adhesion.

Typically, emulsion adhesives require water for suspension of solids. Thus, the more emulsion adhesive used in constructing a waterproofing membrane, the more water is present in the waterproofing membrane before the membrane is even installed. Thus, water has already been introduced to the expandable materials, including Bentonite clay and/or Super Absorbent Polymers, reducing the function of these materials as used in waterproofing membranes. The present invention essentially proportionately reduces this water content and increases overall function of a waterproofing membrane by adhesion of the composition to a selected membrane.

The waterproofing membranes can be manufactured using various methods of layering the waterproofing composition on a base sheet or substrate. Each method serves to provide enhanced properties to the waterproofing membrane once manufactured. Further, a waterproofing membrane may be manufactured using a single layering method or a combination of layering methods depending on the desired characteristics of the waterproofing membrane.

In a preferred method of manufacturing a waterproofing membrane, a topical coat layer is adhered to both a top and a bottom of the waterproofing composition layer. The topical coat layer is applied to add strength and structure the waterproofing composition and waterproofing membrane. A sandwich like structure is formed, wherein a base sheet or substrate is coated with a first topical coat layer. The waterproofing composition is then layered on top of the topical coat structure. A second topical coat layer is then applied thereon. The top and bottom layers are of the same general composition, but variations may be made to either topical layer depending on desired qualities or structural limitations on the base sheet or substrate. The waterproofing composition layer (also referred to as the center or middle layer), as sandwiched between the topical layers and adhered to a base sheet is specifically tailored to the expansion needs of the membrane. The ratio of rubber to expansives as determined by the selected base sheet, desired expansive specifications and an end use of the membrane comprises the middle or center layer. The middle or center layer will expand while retaining its original shape and without twisting, warping or distorting the base sheet or substrate. The middle or center layer may comprise one or more layers of waterproofing composition as discussed previously. Further, each individual layer of waterproofing material comprising the middle or center layer may be of the same or different composition depending on the desired expansive specifications.

Specifications may eliminate the need for topical layers. As such, base sheet adhesion is a method of layering the waterproofing composition on to a base sheet. An example of base sheet adhesion comprises adhesion of a layer of waterproofing composition to a top-side of a base sheet. The base sheet for example, comprising polyethylene.

Further, optimal sheet adhesion to a membrane comprises coating one to three layers of the waterproofing composition, wherein the composition may be a least expansive composition. Coating one to two layers of the waterproofing composition minimizes shear forces between the expansive granules and the rubber granules when the expansives are exposed to water or hydration. Optimal sheet adhesion and multiple layering may be used with or without topical coat layers.

In yet a further embodiment, a middle or center layer may comprise a minimally expansive waterproofing composition layer. Such layers, without topical coat layers, is useful in a product wherein the product is designed to expand in all directions and remain flexible and undistorted after hydration. Thus the membrane will pivot and expand from the center. An example would be a substrate wherein adhesive is coated on both sides.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. 

What is claimed:
 1. A waterproofing membrane system, the system comprising: dry rubber granules; dry expansive material granules; an adhesive; a membrane; and wherein the dry rubber granules are mixed with the dry expansive material granules to form a mixture, the mixture then applied to the membrane in at least a first layer, such that the rubber particles limit expansion of the expandables in at least the first layer when the membrane is introduced to a source of moisture.
 2. The system of claim 1 wherein the expansive granules comprise Bentonite clay particles.
 3. The system of claim 1 wherein the expansive granules comprise super absorbent polymers.
 4. The system of claim wherein the expansive granules comprise both Bentonite clay and super absorbent polymers.
 5. The system of claim 1 wherein the rubber granules comprise recycled automobile tire rubber.
 6. The system of claim 1 wherein the substrate backing is flexible.
 7. The system of claim 1 wherein a first layer of the mixture of the granules and expansive granules is adhered to the membrane by a first adhesive layer and a second layer of the mixture is coated to a second adhesive layer, the second adhesive layer coated on top of the first layer of the mixture.
 8. The system of claim 1 wherein the rubber granules comprise 25-95% of the mixture of rubber granules, adhesive and expansive material granules by weight.
 9. The system of claim 1 wherein the substrate is flexible and having an adhesive coated bottom side wherein the mixture of granules and adhesive are coated on a topside of the substrate.
 10. A method of making an expansive sheet waterproofing system, the method comprising: determining a selected waterproofing and expansion need; pulverizing recycled rubber into granules; drying the rubber granules; mixing the rubber granules with dry granules of expansive material; and applying the mixture of rubber granules and expansive materials as a layer sufficient to meet the determined waterproofing and expansion needs to a substrate having an adhesive coating thereon and the rubber particles limiting expansion of the expansive granules in the layer when exposing the membrane to a source of moisture.
 11. The method of claim 10 wherein the expansive materials comprise Betonite clay.
 12. The method of claim 10 wherein the expansive materials comprise super absorbent polymers.
 13. The method of claim 10 wherein the expansive materials comprise a combination of Betonite clay and super absorbent polymers.
 14. The method of claim 10 wherein the recycled rubber granules comprise recycled automobile tire rubber.
 15. The method of claim 10 and further adding the coated rubber granules to the expansive granules such that the mixture comprises 25-95% rubber particles by weight. 